#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	char killer;
	for (killer = 'A'; killer <= 'D'; killer++)
	{
		int count = 0;
		if (killer != 'A')
			count++;
		if (killer == 'C')
			count++;
		if (killer == 'D')
			count++;
		if (killer != 'D')
			count++;
		if (count == 3)
		{
			printf("%c", killer);
			break;
		}
	}
	return 0;
}
